EP0014043A1 - Fabrication d'un film piézo-électrique et transducteur - Google Patents

Fabrication d'un film piézo-électrique et transducteur Download PDF

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Publication number
EP0014043A1
EP0014043A1 EP80300070A EP80300070A EP0014043A1 EP 0014043 A1 EP0014043 A1 EP 0014043A1 EP 80300070 A EP80300070 A EP 80300070A EP 80300070 A EP80300070 A EP 80300070A EP 0014043 A1 EP0014043 A1 EP 0014043A1
Authority
EP
European Patent Office
Prior art keywords
film
piezo
temperature
electric
electrodes
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP80300070A
Other languages
German (de)
English (en)
Inventor
Norman William Tester
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
International Standard Electric Corp
Original Assignee
International Standard Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB7903224A external-priority patent/GB2040642A/en
Priority claimed from GB7911672A external-priority patent/GB2045522B/en
Application filed by International Standard Electric Corp filed Critical International Standard Electric Corp
Publication of EP0014043A1 publication Critical patent/EP0014043A1/fr
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/85—Piezoelectric or electrostrictive active materials
    • H10N30/857—Macromolecular compositions
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/04—Treatments to modify a piezoelectric or electrostrictive property, e.g. polarisation characteristics, vibration characteristics or mode tuning
    • H10N30/045—Treatments to modify a piezoelectric or electrostrictive property, e.g. polarisation characteristics, vibration characteristics or mode tuning by polarising
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/09—Forming piezoelectric or electrostrictive materials
    • H10N30/098—Forming organic materials

Definitions

  • This invention relates to the manufacture of piezo-electrically active plastics film, commencing with the film material in the "raw” state, and to electro-acoustic or electro-mechanical transducer using such diaphragms.
  • PVDF polyvinylidene fluoride
  • the diaphragm In making the diaphragm for such applications it is necessary to apply electrodes to the two faces of the film material. This is usually performed by vacuum evaporation, which needs expensive equipment. Further, as the film has to be continuously polarized the film is usually electroded over a large proportion of its surface area. However, when the material is to be used, e.g. in a transducer, it is often required that only isolated regions have to be electroded. Hence the metallization has to be partly removed to give the required electrode shape, or the entire electrode must be removed and a new electrode of the required size applied.
  • This invention seeks to overcome the above- mentioned disadvantages.
  • a process for the production of piezo-electric film in which melt-extruded film of the material to be rendered piezo-electric is stretched, which stretching is effected in a direction parallel to the extrusion direction with a stretch ratio and at a temperature such that the material of the film is converted into a form in which it can be rendered piezo-electric; characterized in this, that the film is clamped between layers of conductive rubber or rubber-like material to which is applied a polarizing voltage of a magnitude appropriate to the material to be rendered piezo-electric and to the thickness thereof, the film being held at that temperature for a time appropriate to the production of the desired piezo-electricity, whereafter the film is cooled to room temperature with the polarizing field still applied, that electrodes of an electrically-conductive elastomer are printed or otherwise formed onto the film in the required patterns, said electrodes being applied to one or both sides of the film, and that the piezo-electric properties of the film are stabilized by heating the
  • a diaphragm of this type for use in a transducer requires for its operation that one or both of its surfaces carry electrodes to which electrical contact can be made.
  • electrodes consist of a thin metal film applied by vacuum coating or electroplating methods.
  • the connections to the electrodes are usually pressure contacts, since a soldering or welding operation would damage the plastics foil.
  • most metals that would be otherwise suitable for use as electrodes suffer from one or both of the following problems:
  • an electro-acoustic or electro-mechanical transducer which includes a diaphragm of an electrically active plastics material having electrically conductive electrodes on one or both of its two faces, wherein each said electrode is of an elastomer material having particles of an electrically conductive material dispersed in it.
  • Fluorine- containing polymers are especially suitable for this purpose as they are highly stable and are not damaged by high temperature during use, or during the polarization of the foil.
  • melt-extruded PVDF sheet is stretched uni-axially along the extrusion direction by the natural stretch ratio while the temperature is maintained at less than 120°C. Under these conditions a large part of the mainly amorphous extruded sheet is converted to the p crystalline form, which is suitable to be rendered piezo-electric. At the same time the thickness of the material is reduced to a value suitable for use as transducer diaphragms.
  • a suitable stretching temperature has been found to be 100°C with a stretch ratio of 4 to 1. The stretching is preferably performed continuously by winding the film between two rollers driven at different speeds, the take-up roller being the faster rotating one.
  • the speed at which the film leaves the supply roll and the speed at which it is wound onto the take-up roll are monitored, and a control system is used to maintain the required stretch ratio by varying the speed of one of the two drive motors.
  • the region over which the stretching takes place is heated to the required stretch temperature.
  • the film 1 to be treated is passed from a supply reel 2 through a slot and into a chamber 3, which it leaves via another slot and is wound onto a take-up reel 4.
  • the chamber 3 is heated to the polarization temperature, which is 110°C in the present example.
  • the film is clamped between two endless belts 5 and 6, which run over a series of rollers, such as 7, 8.
  • One of the belts 6 has on its surface a continuous layer of silicone rubber containing carbon particles to render it electrically conductive, and this layer is connected to one terminal of an EHT supply 9.
  • the other belt 5 also has electrically conductive silicone rubber on its surface, but this is applied in electrically isolated regions with an insulative strip such as 12 or a gap a few millimetres wide between each such region. Note here that a gap between the edges of two adjacent silicone rubber regions is in effect an electrically insulative gap.
  • each region of conductive rubber is connected via a resistor such as 14 to the EHT supply 9.
  • resistors such as 14 to the EHT supply 9.
  • the polarization voltage used should be as large as possible, to obtain the maximum piezo-electric effect.
  • the electric field is, however, limited by the dielectric strength of the film to about 10 volts/ metre at a polarizing temperature of 110°C. For a l2 ⁇ m film this means a polarizing voltage of about 1300 volts.
  • the piezo-electric constants increase with polarization time up to a limiting value: in the case of the temperature and field strengths used in the present example, very little improvement in piezo-electric properties is achievable after a polarization time of about 30 mins. Hence the length of the polarization chamber 3 and the speed of travel of the film are such that the film remains in the polarizing field for at least 30 mins.
  • the film After it leaves the heated chamber 3 the film is cooled to 50°C or lower before the polarizing film is removed. This can be seen to be so in the drawing, because of the electrodes 13 which are shown to the right of the exit slot of the chamber 3.
  • the rate of cooling is not important, but to reduce the lengths of the continuous belts needed if natural cooling is used the final clamping rollers may be water cooled.
  • the film may now be wound onto the take-up reel 4, or may pass directly to the stabilization heating stage.
  • This next stage involves heating the film without constraints to stabilize its piezo-electric and mechanical properties. This final heating must be effected at a temperature below the polarization temperature but above any temperature which the material is expected to experience during its subsequent use.
  • the maximum temperature to which a transducer housing a diaphragm of this film is expected to be subjected is 70 0 C r it has been found that subsequent change of sensibility is negligible if the film is stabilized at a temperature of 90°C for 2 hours, after polarization at 110°C. This is achieved by simply passing the film through a heated chamber while allowing some slack within the chamber, so that the material may relax.
  • the polarizing temperature of 110°C is so chosen to achieve a suitable margin above the operation and heat treatment temperatures.
  • Electrodes of conductive elastomer can now be applied by, for example, screen printing to give the patterns required before or subsequent to punching or cutting the required areas from the films, see below.
  • a transducer diaphragm 1 of plastics foil is shown, which is coated on each face with electrodes 2 of a conductive carbon-loaded elastomer.
  • the diaphragm is assumed to be circular, being gripped at the rim, and having electrode connections (not shown) made to the electrodes 2.
  • These electrodes may be applied by brushing, spraying or printing on of the elastomer-carbon mixture which has been dissolved in a suitable solvent. When the solvent evaporates a thin layer of carbon-loaded elastomer is left on the surface of the foil 1.
  • the foil 1 may be piezoelectrically active material or an electret material.
  • elastomer may be applied over the metal electrodes to protect them and also to provide a reliable means of connection.
  • Fig. 3 An example of this is shown in Fig. 3 where metal electrodes 3 on the plastics foil 1 are coated with a carbon-loaded elastomer 2.
  • Fig. 4 shows how electrical contact may be made to an electrode 2 on a foil 1 by clamping it to a metal ring 4 by a frame 5.
  • the ring 4 connected to one transducer terminal may be coated with precious metal or may itself have a coating of carbon-loaded polymer 3 on its contacting surface. Another possibility is to make the clamping material itself out of a conductive plastics material.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Laminated Bodies (AREA)
EP80300070A 1979-01-30 1980-01-08 Fabrication d'un film piézo-électrique et transducteur Withdrawn EP0014043A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB7903224A GB2040642A (en) 1979-01-30 1979-01-30 Transducer
GB7903224 1979-01-30
GB7911672A GB2045522B (en) 1979-04-03 1979-04-03 Piezo-electric film manufacture
GB7911672 1979-04-03

Publications (1)

Publication Number Publication Date
EP0014043A1 true EP0014043A1 (fr) 1980-08-06

Family

ID=26270391

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80300070A Withdrawn EP0014043A1 (fr) 1979-01-30 1980-01-08 Fabrication d'un film piézo-électrique et transducteur

Country Status (5)

Country Link
EP (1) EP0014043A1 (fr)
BR (1) BR8000520A (fr)
DK (1) DK36880A (fr)
IL (1) IL59078A0 (fr)
PL (1) PL221505A1 (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2519503A1 (fr) * 1981-12-31 1983-07-08 Thomson Csf Transducteurs piezoelectriques polymeres et procede de fabrication
EP0085759A1 (fr) * 1982-02-04 1983-08-17 Pennwalt Corporation Fabrication des films piézoélectriques lisses par polarisation
WO1985004513A1 (fr) * 1984-03-26 1985-10-10 American Telephone & Telegraph Company Procede de production de dispositifs contenant des electrets
EP0174838A2 (fr) * 1984-09-11 1986-03-19 Focas Limited Polymères en fluorure de vinylidène piézoélectrique stabilisé
DE4136269A1 (de) * 1991-11-04 1993-05-06 Odermath Stahlwerkstechnik Gmbh, 4019 Monheim, De Vorrichtung zum liegenden transport und zur liegenden lagerung einer drahtspule
EP0911784A1 (fr) * 1997-10-22 1999-04-28 Gunnar Matschulat Dispositif de lecture tactille
EP1215737A2 (fr) * 2000-12-15 2002-06-19 Matsushita Electric Industrial Co., Ltd. Appareil de polarisation et procédé de polarisation pour un câble coaxial piézoélectrique flexible
WO2005086528A1 (fr) * 2004-03-04 2005-09-15 Mirae Plasma Co., Ltd. Procede permettant de produire un haut-parleur ultramince comprenant une feuille piezo-electrique et appareil de sonorisation comprenant ce haut-parleur

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1497727A (fr) * 1966-10-17 1967-10-13 Philip Morris Inc Procédé de fabrication de matériau porteur de charges et produit fabriqué par ce procédé
US3449094A (en) * 1965-10-23 1969-06-10 Philip Morris Inc Laminated electrets
FR2275033A1 (fr) * 1974-06-17 1976-01-09 Minnesota Mining & Mfg Machine et procede de polarisation
FR2284992A1 (fr) * 1974-09-11 1976-04-09 Kureha Chemical Ind Co Ltd Procede de polarisation en continu de films thermoplastiques

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3449094A (en) * 1965-10-23 1969-06-10 Philip Morris Inc Laminated electrets
FR1497727A (fr) * 1966-10-17 1967-10-13 Philip Morris Inc Procédé de fabrication de matériau porteur de charges et produit fabriqué par ce procédé
FR2275033A1 (fr) * 1974-06-17 1976-01-09 Minnesota Mining & Mfg Machine et procede de polarisation
GB1501921A (en) * 1974-06-17 1978-02-22 Minnesota Mining & Mfg Poling machine
FR2284992A1 (fr) * 1974-09-11 1976-04-09 Kureha Chemical Ind Co Ltd Procede de polarisation en continu de films thermoplastiques
GB1507326A (en) * 1974-09-11 1978-04-12 Kureha Chemical Ind Co Ltd Method for continuously polarizing thermoplastic film

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2519503A1 (fr) * 1981-12-31 1983-07-08 Thomson Csf Transducteurs piezoelectriques polymeres et procede de fabrication
EP0086922A1 (fr) * 1981-12-31 1983-08-31 Thomson-Csf Procédé de fabrication de transducteurs piézo-électriques polymères
EP0085759A1 (fr) * 1982-02-04 1983-08-17 Pennwalt Corporation Fabrication des films piézoélectriques lisses par polarisation
WO1985004513A1 (fr) * 1984-03-26 1985-10-10 American Telephone & Telegraph Company Procede de production de dispositifs contenant des electrets
EP0159147A1 (fr) * 1984-03-26 1985-10-23 AT&T Corp. Procédé de fabrication de dispositifs à électrète
EP0174838A2 (fr) * 1984-09-11 1986-03-19 Focas Limited Polymères en fluorure de vinylidène piézoélectrique stabilisé
EP0174838A3 (fr) * 1984-09-11 1989-08-02 Focas Limited Polymères en fluorure de vinylidène piézoélectrique stabilisé
DE4136269A1 (de) * 1991-11-04 1993-05-06 Odermath Stahlwerkstechnik Gmbh, 4019 Monheim, De Vorrichtung zum liegenden transport und zur liegenden lagerung einer drahtspule
EP0911784A1 (fr) * 1997-10-22 1999-04-28 Gunnar Matschulat Dispositif de lecture tactille
EP1215737A2 (fr) * 2000-12-15 2002-06-19 Matsushita Electric Industrial Co., Ltd. Appareil de polarisation et procédé de polarisation pour un câble coaxial piézoélectrique flexible
EP1215737A3 (fr) * 2000-12-15 2005-05-11 Matsushita Electric Industrial Co., Ltd. Appareil de polarisation et procédé de polarisation pour un câble coaxial piézoélectrique flexible
WO2005086528A1 (fr) * 2004-03-04 2005-09-15 Mirae Plasma Co., Ltd. Procede permettant de produire un haut-parleur ultramince comprenant une feuille piezo-electrique et appareil de sonorisation comprenant ce haut-parleur

Also Published As

Publication number Publication date
DK36880A (da) 1980-07-31
BR8000520A (pt) 1980-10-14
PL221505A1 (fr) 1980-09-22
IL59078A0 (en) 1980-05-30

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Inventor name: TESTER, NORMAN WILLIAM